On-line estimation of local oscillator noise and optimisation of servo parameters in atomic clocks

authored by: Ian D. Leroux, Nils Scharnhorst, Stephan Hannig, Johannes Kramer, Lennart Pelzer, Mariia Stepanova, Piet Oliver Schmidt
Abstract: For atomic frequency standards in which fluctuations of the local oscillator (LO) frequency are the dominant noise source, we examine the role of the the servo algorithm that predicts and corrects these frequency fluctuations. We derive the optimal linear prediction algorithm, showing how to measure the relevant spectral properties of the noise and optimise servo parameters while the standard is running, using only the atomic error signal. We find that, for realistic LO noise spectra, a conventional integrating servo with a properly chosen gain performs nearly as well as the optimal linear predictor. Using simple analytical models and numerical simulations, we establish optimum probe times as a function of clock atom number and of the dominant noise type in the local oscillator. We calculate the resulting LO-dependent scaling of achievable clock stability with atom number for product states as well as for maximally-correlated states.
Organisation(s): Institute of Quantum Optics
CRC 1227 Designed Quantum States of Matter (DQ-mat)
External Organisation(s): Physikalisch-Technische Bundesanstalt PTB
National Research Council of Canada
Type: Article
Journal: Metrologia
Volume: 54
Pages: 307-321
No. of pages: 15
ISSN: 0026-1394
Publication date: 05.03.2017
Publication status: Published
Peer reviewed: Yes
ASJC Scopus subject areas: General Engineering
Electronic version(s): https://doi.org/10.1088/1681-7575/aa66e9 (Access: Open)

BibTeX

@article{0765b09d64da41c2977754d043e2079d,
title = "On-line estimation of local oscillator noise and optimisation of servo parameters in atomic clocks",
abstract = "For atomic frequency standards in which fluctuations of the local oscillator (LO) frequency are the dominant noise source, we examine the role of the the servo algorithm that predicts and corrects these frequency fluctuations. We derive the optimal linear prediction algorithm, showing how to measure the relevant spectral properties of the noise and optimise servo parameters while the standard is running, using only the atomic error signal. We find that, for realistic LO noise spectra, a conventional integrating servo with a properly chosen gain performs nearly as well as the optimal linear predictor. Using simple analytical models and numerical simulations, we establish optimum probe times as a function of clock atom number and of the dominant noise type in the local oscillator. We calculate the resulting LO-dependent scaling of achievable clock stability with atom number for product states as well as for maximally-correlated states.",
keywords = "Atomic frequency standards, Local oscillator noise, Quantum projection noise, Servo optimisation",
author = "Leroux, {Ian D.} and Nils Scharnhorst and Stephan Hannig and Johannes Kramer and Lennart Pelzer and Mariia Stepanova and Schmidt, {Piet Oliver}",
year = "2017",
month = mar,
day = "5",
doi = "10.1088/1681-7575/aa66e9",
language = "English",
volume = "54",
pages = "307--321",
journal = "Metrologia",
issn = "0026-1394",
publisher = "IOP Publishing Ltd.",
number = "3",
}